Preparation Of ZnO Nanofilm And Its Application In UV-modulated Room Temperature NO₂ Gas Sensor

NO₂ gas sensor can be used to detect NO₂ content in living environment or industrial production,and provide reference for people's healthy life.Developing of low-power and room temperature NO₂ gas sensors are research hotspot.In this paper,the effect of UV?ultraviolet?light with different light intensity on the performance of ZnO nanofilm room temperature NO₂ gas sensor was studied.Finally,ZnO nanofilm room temperature NO₂ gas sensor which has high sensitivity and short recovery time is fabricated,and the reason for the high sensitivity of the sensor is explained.ZnO nanofilm with rich oxygen vancancies is fabricated on a variety of substrates,and the thick of ZnO nanofilm is 15 nm,which makes ZnO nanofilm an ideal material for fabricating NO₂ gas sensors.The NO₂ gas sensor is fabricated using ZnO nanofilm.However,at room temperature in the dark,the sensitivity of the device is low and the device cannot recover in a short time.In order to improve the sensitivity and recovery speed of the device,continuous irradiating ultraviolet light with a wavelength of 365 nm is used to make the device work normally.The sensitivity of the device based on ZnO nanofilm to NO₂ gas under different light intensity ultraviolet light is explored.It is found that as the intensity of ultraviolet light increases,the sensitivity of the device increases at first and then decreases.It is due to the fact that the ratio of electron captured by adsorped NO₂ to the amount of photo-induced electron first increases and then decreases under different UV light intensities.Under optimal illumination with an ultraviolet light intensity of 25?W cm^-2,ZnO nanofilm room temperature NO₂ gas sensor's sensitivity to 100 ppm NO₂ is 574,which is 64 times that of the device in the dark.The response time of the device working under UV illuminination is one third of the device working in the dark,and the device can recover within 163 s.Through theoretical analysis and experimental investigation,it is found that the high sensitivity of ZnO nanofilm room temperature NO₂ gas sensor is determined by the characteristics of small thickness and high surface oxygen vacancy density of ZnO nanofilm.